Alt hold problems

Hi everyone, when i’m using the althold mode the throttle only moves above the mid point and isn’t as sensitive. Also to mention that the motor spins when it is armed, is it normal?

Yes, all that is normal.
You need to read through the documentation here

In Alt Hold the centre throttle position means stay at that altitude, up is increase altitude, and below half is decrease.

It’s all explained in the documentation.